WARSAW, Poland (AP) — A leak was detected in an oil pipeline in Poland which is the main route through which Russian crude oil reaches Germany, the Polish operator said Wednesday.

The operator, PERN, said it detected a leak in the Druzhba pipeline, which originates in Russia, on Tuesday evening about 70 kilometers (45 miles) form the the central Polish city of Plock. It said the cause of the leak wasn't known.

The incident follows leaks late last month in the Nord Stream 1 and 2 gas pipelines running along the Baltic seabed.